Fix a crash in strncpy/stpncpystrn

```
Core was generated by `scripts/mod/modpost -M -m -o Module.symvers -n -T modules.order vmlinux.o'.
Program terminated with signal SIGSEGV, Segmentation fault.
warning: 17     src/string/strlen.c: No such file or directory
(gdb) bt
```

> I think strncpy logic is broken: `__fh_size_t max_len_s = strlen(__s);` may try read past `size_t __n`.
> Create a buf without any trailing `\0`, do `strncpy(dest, buf, sizeof(buf));`, it should work, since `strncpy` will stop at `sizeof buf`
> but the current fority-headers implementation will do `strlen(buf)`, which will go boom when it is not terminated with \0

Reported-by: ncopa

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/test_stpncpy_dynamic_write.c b/tests/test_stpncpy_dynamic_write.c
index 14f6fd9..d315ee8 100644
--- a/tests/test_stpncpy_dynamic_write.c
+++ b/tests/test_stpncpy_dynamic_write.c
@@ -3,7 +3,7 @@
 #include <string.h>
 
 int main(int argc, char** argv) {
-  char buffer[] = {'A', 'B', 'C', 'D', 'E', 'F', '\0'};
+  char buffer[] = {'A', 'B', 'C', 'D', 'E', 'F'};
 
   stpncpy(buffer, "1234567", 3);
   puts(buffer);